In order to improve the environment of grinding working for metro lines and realize the utilization of catenary and internal combustion hybrid power, a hybrid metro rail grinding wagon was developed. The basic composition, functions and principles of each subsystem of the grinding wagon were introduced in detail. The problem of exhaust gas discharging and noise pollution could be effectively solved by grinding working with the catenary power in tunnel. The application practice of Changsha metro showed that the catenary power grinding equipment has the advantages of zero emission and low noise.